Lecture Notes on Oat Milk Production and Processing Equipment

Hochschule für Agrar Forst- und Lebensmittelwissenschaften HAFL

  • Institution: Hochschule für Agrar Forst- und Lebensmittelwissenschaften (HAFL)

  • Location: Bern, Switzerland

Oat Milk Production Process

  • Liquefaction: First step involving the breakdown of oat starches.

    • Enzyme: Liquefaction enzyme is crucial for this process.

    • Water addition: Oat flour is mixed with water in a ratio of 1:4 to 1:6.

    • Heat Treatment: The mixture undergoes heat treatment in a liquefaction tank at temperatures between 80-95°C, depending on the specific enzyme used.

    • Cooling: The temperature is then cooled to 60-65°C.

    • Saccharification: At this cooling stage, a saccharification enzyme is added.

    • Conditions: This process runs at 50-65°C for 15-60 minutes, again depending on the enzyme.

  • Decanting/Centrifugation:

    • Following saccharification, the mixture is decanted or centrifuged to separate solids from liquids.

    • Formulation: In the formulation tank, ingredients such as NaCl, oil, and flavors are added.

  • Homogenization:

    • The mixture is subjected to a homogenization process to create a stable product.

  • UHT/ESL Packaging Treatment:

    • Finally, the oat milk is packaged using ultra-high-temperature (UHT) or extended shelf life (ESL) treatment.

Colloid Mill

  • Definition: A colloid mill is a mechanical device that reduces the size of solid particles dispersed in a liquid, creating a uniform and stable mixture.

  • Operational Principle: It operates based on shearing and grinding principles.

  • Components:

    • Rotor and Stator: The milling apparatus consists of a rotor that rotates at high speed and a stationary stator positioned very close to the rotor.

  • Process:

    1. Feed: The material is introduced into the mill.

    2. Shearing and Grinding: The rotor creates intense shearing forces. The narrow gap between the rotor and stator places the material under mechanical stress, breaking it down into finer particles.

Enzymatic Processes in Oat Milk Production

  • Alpha-Amylase:

    • Function: Alpha-amylase breaks down starch molecules into smaller units called dextrins.

    • Process: Once added to oat milk, it targets starch, converting it into dextrins. This breakdown reduces viscosity and improves the texture of the milk.

  • Glucoamylase:

    • Function: Glucoamylase further reduces dextrins into glucose molecules.

    • Process: Post alpha-amylase action, glucoamylase converts dextrins into glucose, which enhances sweetness and contributes to a smoother consistency of oat milk.

Decanter

  • Definition: A decanter is a centrifuge that separates solid particles from liquid based on density differences by spinning the mixture at high speeds.

  • Components:

    • Rotating Bowl: The primary component that spins at high speeds.

    • Scroll: An endless screw inside the bowl that moves solids towards the discharge end.

  • Process:

    1. Feed: The mixture of solids and liquids is introduced into the decanter.

    2. Centrifugal Force: High-speed rotation generates centrifugal force, pushing heavier solids outward against the bowl walls, while the lighter liquid remains towards the center.

    3. Separation: The scroll moves the solids to the discharge end, where they are expelled, while the liquid is removed from a separate outlet.

Homogenizer

  • Definition: A homogenizer is a device that produces a stable and uniform mixture by reducing the size of fat molecules and other particles through high-pressure shearing.

  • Components:

    • High-Pressure Pump: Forces the mixture through a narrow gap for homogenization.

    • Homogenizing Valve: The mixture passes through this valve, where pressure and turbulence break down particles.

  • Process:

    1. Feed: The mixture is introduced into the homogenizer.

    2. High-Pressure Shearing: The high-pressure pump propels the mixture through the homogenizing valve where intense forces break down fat molecules and particles.

Particle Size Analysis

  • Method: Laser diffraction analysis is employed to measure particle sizes.

    • Working Principle: Scattered or diffracted light is recorded across a broad range of angles using a specialized laser and detector setup.

    • Observation: Larger particles scatter light at smaller angles, while smaller particles achieve maximum scattering at larger angles.

Acidification in Yogurt Formation

  • Glucono-delta-lactone (GDL): GDL undergoes hydrolysis in water to form gluconic acid.

    • Process: The gradual release of acid reduces the mixture's pH, fostering an acidic environment essential for yogurt fermentation.

    • Importance: Acidification is a key step in yogurt production, impacting texture and flavor.